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Subject[PATCH 2/2] KVM: x86: Add nested virtualization support for MPX
Date
This is simple to do, the "host" BNDCFGS is either 0 or the guest value.
However, both controls have to be present. We cannot provide MPX if
we only have one of the "load BNDCFGS" or "clear BNDCFGS" controls.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/kvm/vmx.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 729b1e42aded..da28ac46ca88 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -202,6 +202,7 @@ struct __packed vmcs12 {
u64 guest_pdptr1;
u64 guest_pdptr2;
u64 guest_pdptr3;
+ u64 guest_bndcfgs;
u64 host_ia32_pat;
u64 host_ia32_efer;
u64 host_ia32_perf_global_ctrl;
@@ -534,6 +535,7 @@ static const unsigned long shadow_read_write_fields[] = {
GUEST_CS_LIMIT,
GUEST_CS_BASE,
GUEST_ES_BASE,
+ GUEST_BNDCFGS,
CR0_GUEST_HOST_MASK,
CR0_READ_SHADOW,
CR4_READ_SHADOW,
@@ -589,6 +591,7 @@ static const unsigned short vmcs_field_to_offset_table[] = {
FIELD64(GUEST_PDPTR1, guest_pdptr1),
FIELD64(GUEST_PDPTR2, guest_pdptr2),
FIELD64(GUEST_PDPTR3, guest_pdptr3),
+ FIELD64(GUEST_BNDCFGS, guest_bndcfgs),
FIELD64(HOST_IA32_PAT, host_ia32_pat),
FIELD64(HOST_IA32_EFER, host_ia32_efer),
FIELD64(HOST_IA32_PERF_GLOBAL_CTRL, host_ia32_perf_global_ctrl),
@@ -719,6 +722,7 @@ static unsigned long nested_ept_get_cr3(struct kvm_vcpu *vcpu);
static u64 construct_eptp(unsigned long root_hpa);
static void kvm_cpu_vmxon(u64 addr);
static void kvm_cpu_vmxoff(void);
+static bool vmx_mpx_supported(void);
static int vmx_set_tss_addr(struct kvm *kvm, unsigned int addr);
static void vmx_set_segment(struct kvm_vcpu *vcpu,
struct kvm_segment *var, int seg);
@@ -2279,6 +2283,8 @@ static __init void nested_vmx_setup_ctls_msrs(void)
}
nested_vmx_exit_ctls_high |= (VM_EXIT_ALWAYSON_WITHOUT_TRUE_MSR |
VM_EXIT_LOAD_IA32_EFER | VM_EXIT_SAVE_IA32_EFER);
+ if (vmx_mpx_supported())
+ nested_vmx_exit_ctls_high |= VM_EXIT_CLEAR_BNDCFGS;

/* entry controls */
rdmsr(MSR_IA32_VMX_ENTRY_CTLS,
@@ -2292,6 +2298,8 @@ static __init void nested_vmx_setup_ctls_msrs(void)
VM_ENTRY_LOAD_IA32_PAT;
nested_vmx_entry_ctls_high |= (VM_ENTRY_ALWAYSON_WITHOUT_TRUE_MSR |
VM_ENTRY_LOAD_IA32_EFER);
+ if (vmx_mpx_supported())
+ nested_vmx_entry_ctls_high |= VM_ENTRY_LOAD_BNDCFGS;

/* cpu-based controls */
rdmsr(MSR_IA32_VMX_PROCBASED_CTLS,
@@ -7847,6 +7855,9 @@ static void prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)

set_cr4_guest_host_mask(vmx);

+ if (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_BNDCFGS)
+ vmcs_write64(GUEST_BNDCFGS, vmcs12->guest_bndcfgs);
+
if (vmcs12->cpu_based_vm_exec_control & CPU_BASED_USE_TSC_OFFSETING)
vmcs_write64(TSC_OFFSET,
vmx->nested.vmcs01_tsc_offset + vmcs12->tsc_offset);
@@ -8277,6 +8288,7 @@ static void prepare_vmcs12(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12,
vmcs12->guest_sysenter_cs = vmcs_read32(GUEST_SYSENTER_CS);
vmcs12->guest_sysenter_esp = vmcs_readl(GUEST_SYSENTER_ESP);
vmcs12->guest_sysenter_eip = vmcs_readl(GUEST_SYSENTER_EIP);
+ vmcs12->guest_bndcfgs = vmcs_readl(GUEST_BNDCFGS);

/* update exit information fields: */

@@ -8386,6 +8398,10 @@ static void load_vmcs12_host_state(struct kvm_vcpu *vcpu,
vmcs_writel(GUEST_IDTR_BASE, vmcs12->host_idtr_base);
vmcs_writel(GUEST_GDTR_BASE, vmcs12->host_gdtr_base);

+ /* If not VM_EXIT_CLEAR_BNDCFGS, the L2 value propagates to L1. */
+ if (vmcs12->vm_exit_controls & VM_EXIT_CLEAR_BNDCFGS)
+ vmcs_write64(GUEST_BNDCFGS, 0);
+
if (vmcs12->vm_exit_controls & VM_EXIT_LOAD_IA32_PAT) {
vmcs_write64(GUEST_IA32_PAT, vmcs12->host_ia32_pat);
vcpu->arch.pat = vmcs12->host_ia32_pat;
--
1.8.3.1


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